Semileptonic decays of d mesons in three-flavor lattice QCD

We present the first three-flavor lattice QCD calculations for D-->pilnu and D-->Klnu semileptonic decays. Simulations are carried out using ensembles of unquenched gauge fields generated by the MILC Collaboration. With an improved staggered action for light quarks, we are able to simulate at light quark masses down to 1/8 of the strange mass. Consequently, the systematic error from the chiral extrapolation is much smaller than in previous calculations with Wilson-type light quarks. Our results for the form factors at q(2)=0 are f(D-->pi)(+)(0)=0.64(3)(6) and f(D-->K)(+)(0)=0.73(3)(7), where the first error is statistical and the second is systematic, added in quadrature. Combining our results with experimental branching ratios, we obtain the Cabibbo-Kobayashi-Maskawa matrix elements |V(cd)|=0.239(10)(24)(20) and |V(cs)|=0.969(39)(94)(24), where the last errors are from experimental uncertainties.     

Shubnikov-de haas type oscillations in the optical transmission of highly doped Cd3As2

It has been found that the Fermi energy of thin single crystals of Cd₃As₂ increases to 0.25 eV on annealing under vacuum at 425°C and then decreases to below any previously reported value. The magneto optical measurements which yielded oscillations independent of photon energy were analysed in terms of Shubnikov de Haas oscillations and were consistent with the Bodnar model for the conduction band of Cd₃As₂.     

Monotone trajectories of multivalued dynamical systems

Summary We prove existence of ? monotone trajectories ? for a class of discrete and continuous systems sufficiently general to include problems of some interest in economic and biological theory. We prove existence of critical points which are Pareto minima. We study stability properties of Pareto minima. Entrata in Redazione il 7 settembre 1976. Sponsored in part by ARO Grant DAHC04-74-60012, and NSF MCS75-21868.     

A benzyloxy group migration under Mitsunobu reaction conditions

When compounds 3a and 3b were subjected to a Mitsunobu reaction with benzoylthymine, the expected substitution products were formed together with the regioisomers corresponding to benzyloxy group migrations.     

Synthesis of [323]-p-octiphenyls: orthogonal functionalization along a rigid-rod scaffold for refined supramolecular architecture

[structure: see text] The synthesis of p-octiphenyls carrying orthogonal tert-butyl esters in the peripheral positions 1(2), 2(2), 3(3), 6(2), 7(3), and 8(2) and either p-methoxybenzyl or benzyl ester substituents in the central positions 4(2) and 5(3) is described. Resolution-enhanced HSQC/HMBC two-dimensional NMR spectroscopy is implemented as an attractive method for the complete characterization of complex p-oligophenyl scaffolds.     

Andreev Bound States at the Onset of Phase Coherence in Bi(2)Sr(2)CaCu(2)O(8)

A new technique of planar tunneling spectroscopy has been developed to access the in-plane density of states of optimally doped Bi(2)Sr(2)CaCu(2)O(8) single crystals. The low energy spectrum is observed to depend on crystallographic orientation. When tunnel current is injected nominally along the Cu-Cu bond direction, a zero-bias conductance peak is observed to appear simultaneously with the onset of bulk superconductivity. These data demonstrate the existence of surface-induced states in this system and confirm the d-wave symmetry of the superconducting order parameter.     

(1R,2s,3S,6R,9S)‐5,5,10,10‐Tetrachloro‐2‐methyltricyclo[7.2.0.03,6]undec‐7‐ene‐4,11‐dione

The title compound, C₁₂H₁₀Cl₄O₂, has a pseudoasymmetric centre at the methyl‐substituted carbon and, in the solid state, a boat‐like conformation.     

Stereoselective Multiple Bond‐Forming Transformations (MBFTs): The Power of 1,2‐ and 1,3‐Dicarbonyl Compounds

Although long known, 1,2‐ and 1,3‐dicarbonyl compounds have recently come more and more to prevalence as ideal substrates for the invention of new stereoselective multiple bond‐forming transformations (MBFTs). Herein, a critical appraisal is presented of some of the most spectacular of these MBFTs, which allow the formation from three up to six bonds in highly step‐ and atom‐economical processes.     

Non‐Aqueous Sol–Gel Synthesis of Ultra Small Persistent Luminescence Nanoparticles for Near‐Infrared In Vivo Imaging

Ultra‐small ZnGa₂O₄:Cr³⁺ nanoparticles (6 nm) that exhibit near‐infrared (NIR) persistent luminescence properties are synthesized by using a non‐aqueous sol–gel method assisted by microwave irradiation. The nanoparticles are pegylated, leading to highly stable dispersions under physiological conditions. Preliminary in vivo studies show the high potential for these ultra‐small ZnGa₂O₄:Cr³⁺ nanoparticles to be used as in vivo optical nanotools as they emit without the need for in situ excitation and, thus, avoid the autofluorescence of tissues.